CN112487632A - Low sidelobe array antenna structure and design method - Google Patents

Low sidelobe array antenna structure and design method Download PDF

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CN112487632A
CN112487632A CN202011339428.0A CN202011339428A CN112487632A CN 112487632 A CN112487632 A CN 112487632A CN 202011339428 A CN202011339428 A CN 202011339428A CN 112487632 A CN112487632 A CN 112487632A
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antenna
array
excitation amplitude
coupling groove
antenna element
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张峰干
姚敏立
伍宗伟
戴精科
王旭建
徐统民
潘蕾
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Rocket Force University of Engineering of PLA
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    • H01Q—ANTENNAS, i.e. RADIO AERIALS
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    • H01—ELECTRIC ELEMENTS
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Abstract

The invention has disclosed a low side lobe array antenna design method specifically, namely construct a parallel array antenna of the interval of non-uniform antenna element, its design method adopts the difference optimization algorithm, get the antenna array element interval distribution and optimum solution of each antenna array element excitation amplitude that makes the level of the side lobe lowest, set up the antenna element in the optimum solution position of the interval distribution of the antenna array element, the slotting length of the coupling slot of the antenna element is established according to the optimum solution to obtain the excitation amplitude, establish the microstrip feeder line length of the feed network of the antenna element according to the optimum solution to obtain the interval distribution of the antenna array element; the invention also discloses a low sidelobe array antenna structure; the method has the advantages that the side lobe of the array antenna is reduced by changing the distance between the antenna units, the poynting vector method is applied to the design of the coupling groove, the side lobe is further reduced, errors in actual antenna processing are made up by designing the adjustable microstrip feeder line during antenna testing, and the performance of the antenna is improved.

Description

Low sidelobe array antenna structure and design method
Technical Field
The invention belongs to the field of array antenna design, and particularly relates to a low-sidelobe array antenna structure and a design method.
Background
The radiation characteristic of the array antenna depends on 5 major factors, namely the radiation characteristic of the antenna units, the distance between the antenna units, the number of the antenna units, the arrangement mode and the excitation of the antenna units; when designing a low-sidelobe antenna, there is no large choice space for factors such as the number of antenna elements and the arrangement due to size limitations, and the analysis method is usually used to concentrate on the quantitative change of the excitation amplitude of the antenna elements, so that the influence of the antenna element spacing on the directivity diagram is ignored. Array antennas are generally divided into two types, namely uniform-spacing array antennas and non-uniform-spacing array antennas, the uniform-spacing antenna array antennas have consistent structures, the theoretical analysis is simple, the antenna scale is easy to expand, but the single high gain and narrow beam width need to increase the antenna aperture, and the increase of the aperture means that more antenna units are used, so that the antenna system is complex in design, the power consumption is increased, the cost is increased, and a series of problems are brought to the array antenna design, for example, the sidelobe level of the antenna is higher, the effective output power is limited, and the transmission information rate is lower; due to the fact that the intervals of the antenna units are unequal, the antenna introduces new variables, the design freedom degree is increased, the antenna unit placed at a specific interval can directly reduce the level of the antenna side lobe, and amplitude weighting is not needed to be carried out on the excitation of the antenna unit; if the distance between the antenna units and the excitation amplitude are combined, the level of a side lobe of the antenna can be further reduced, the interference of a transmission signal to the antenna can be reduced, and meanwhile, the transmission energy can be concentrated in a main lobe of a wave beam.
Disclosure of Invention
Aiming at the existing problems, the invention provides a low sidelobe array antenna structure and a design method thereof, so as to solve the defects of the prior art.
The technical scheme adopted by the invention is as follows:
a design method of a low sidelobe array antenna is characterized in that a parallel array antenna with non-uniform antenna element spacing is constructed, the design method adopts a differential optimization algorithm to obtain the antenna array element spacing distribution with the lowest sidelobe level and the optimal solution of the excitation amplitude of each antenna array element, an antenna element is arranged at the optimal solution position of the antenna array element spacing distribution, the slotting length of a coupling slot of the antenna element is determined according to the optimal solution of the excitation amplitude, and the microstrip feeder line length of a feed network of the antenna element is determined according to the optimal solution of the antenna array element spacing.
Further, the optimal solution solving process of the antenna array element spacing distribution and the excitation amplitude is as follows:
step 1: an array antenna pattern function is determined from an Array Factor (AF) function,
Figure BDA0002798191560000021
in the formula: x is the number ofnIs from the nth array element distributed along the central line of the array antenna to the linear central position of the array antenna, InIs the normalized excitation amplitude of the nth array element, k is 2 pi/λ, λ is the spatial wavelength, and u is sin θ θ is the azimuth;
step 2: calculating the sidelobe level PSLL (PeakSideLobeLevel) of the peak value, wherein the formula is as follows:
Figure BDA0002798191560000022
in the formula: u. ofsFor side lobe ranges other than main lobe peak, AF (u)s) For any side lobe level, x ═ x1,x2,···,xn]Is the position of an array element;
and step 3: with dmin≥0.5,d max1 or less and
Figure BDA0002798191560000023
taking the minimum sidelobe level PSLL of the formula (2) as an optimization target as a constraint condition, adopting a differential optimization algorithm, and taking a final target function formula as follows:
Figure BDA0002798191560000024
in the formula: dminNormalizing the minimum spacing, d, for the array elementsmaxNormalizing the maximum spacing for the array elements;
solving the objective function to find a group of optimal solutions x ═ x satisfying the optimization objective1,x2,···,xn]，I＝[I1,22,···,In]Obtaining the spacing distribution of the antenna array elements and the excitation amplitude of each array element;
and arranging antenna units at the positions of the obtained antenna array element spacing distribution.
Further, the antenna unit is three-layer structure, by supreme bottom base plate, intermediate level, top layer base plate of including in proper order down, the bottom surface of bottom base plate sets up the microstrip feeder, and bottom base plate top surface sets up ground plate and coupling groove, the intermediate level is the air bed, the patch antenna array element is placed to the bottom surface of top layer base plate.
Further, the coupling slot determination process is as follows:
step 1: the coupling groove is an H-shaped coupling groove, the poynting vector S of the groove part of the H-shaped coupling groove points to two sides from the center, and the vector direction of the S is approximately vertical to the plane of the H-shaped coupling groove;
step 2: the energy W is related to the poynting vector S,
Figure BDA0002798191560000031
in the formula: a is H open slot closed space;
the energy of the H-type coupling slot is calculated by equation (4).
And step 3: under the condition that the size of an array element of the patch antenna is fixed, the length of the middle slotted part of the minimum H-shaped coupling groove and the length increasing value of the middle slotted part of the H-shaped coupling groove are set, the proportional relation between the lengths of different H-shaped coupling grooves and the excitation amplitude is obtained through energy calculation of a formula (4), the length of the middle slotted part of a group of H-shaped coupling grooves is selected to be matched with the required optimal excitation amplitude, and the length of the H-shaped coupling groove is designed.
Furthermore, the feed network is formed by cascading T-shaped power dividers, microstrip feed lines are arranged at the output ends of the feed lines of all branches of the T-shaped power dividers, the microstrip feed lines extend to the bottom surface of the bottom substrate of the antenna unit, the lengths of the microstrip feed lines of all branches are unequal and adjustable, and the mathematical relationship of the lengths of the microstrip feed lines is determined based on the positions of the array elements.
The utility model provides a low side lobe array antenna structure, includes a N antenna element and feed network, a N antenna element centrosymmetric inhomogeneous distribution, antenna element is three layer construction, including bottom substrate, intermediate level, top layer substrate, bottom substrate's bottom surface is the microstrip feeder, and bottom substrate top surface sets up ground plate and coupling groove, the intermediate level is the air bed, patch antenna array element is placed to top layer substrate's bottom surface, patch antenna array element sets up to square, the coupling groove center sets up at square center, and the microstrip feeder feeds in from paster edge center, and the perpendicular to the coupling groove, feed network divides the ware to cascade for a plurality of T types merit, the microstrip feeder sets up the output at a plurality of T types merit and divides the ware.
Further, the bottom substrate has a thickness h10.254mm, dielectric constant εrA RogersRT5800 substrate with 2.2 and tan delta of 0.0009, the top substrate being a thickness h3A 0.787mm rogerstr 5800 substrate.
Further, the antenna unit N is set to 8, the distance between two antenna units with central symmetry is 0.7 λ, the excitation amplitude is 1, the distances between the antenna units distributed to two ends in sequence and the previous antenna unit are 0.72 λ, 0.75 λ and 0.77 λ, and the corresponding excitation amplitudes are 0.89, 0.64 and 0.4.
Further, the coupling grooves are H-shaped, and the lengths of the H-shaped grooves are 4.5mm, 4mm, 3.8mm, and 3.2 mm.
Compared with the prior art, the invention has the beneficial effects that: the side lobe of the array antenna is reduced by changing the distance between the antenna units, and the poynting vector method is applied to the design of the coupling slot to further reduce the side lobe.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1, procedure for constructing non-uniform pitch array antenna
FIG. 2, 2N array element non-uniform spacing array antenna schematic diagram
FIG. 3, perspective view of antenna unit (a) top and side views of antenna unit (b)
FIG. 4 shows the voltage standing wave ratio of the H-shaped coupling slot antenna unit
FIG. 5, H-shape coupling slot antenna unit directional diagram
FIG. 6, T-shaped power divider
Fig. 7, 8 array element parallel feed network branch structure relation
Fig. 8, 8 array element antenna feed network cascade structure simulation diagram
Power distribution and phase value of feeding network port of 8-element antenna in fig. 9
FIG. 10, poynting vector
FIG. 11 is a low sidelobe array antenna pictorial representation
FIG. 12, 8 array element antenna voltage standing wave ratio simulation and actual measurement comparison
Fig. 13, simulation and actual measurement results of directional diagram characteristics of antenna observed from three frequency points of 14, 14.25 and 14.5GHz
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance, and furthermore, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or overhanging, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Referring to fig. 1, the invention specifically discloses a design method of a low-sidelobe array antenna, which constructs a non-uniform spacing array antenna and comprises the following steps;
the module 100 sets antenna requirement parameters according to engineering design requirements, and the specific parameters include a working frequency band, a center frequency, a bandwidth, a polarization mode, an array form, a radiation direction, an antenna gain and the like.
The module 101 selects the antenna substrate material, the thickness, the shape and the size of the antenna units, and the number of the antenna units;
the module 102 obtains the antenna array element spacing distribution with the lowest sidelobe level and the optimal solution of each antenna array element excitation amplitude by adopting a differential optimization algorithm, and an antenna unit is arranged at the optimal solution position of the antenna array element spacing distribution;
the module 103 determines the slot length of the coupling slot of the antenna unit according to the optimal solution of the obtained excitation amplitude;
the module 104 establishes the microstrip feed line length of the antenna unit feed network according to the obtained optimal solution of the antenna array element spacing distribution.
Specifically, the optimal solution solving process of the antenna array element spacing and the excitation amplitude in the module 102 is as follows:
step 1: an array antenna pattern function is determined from an Array Factor (AF) function,
Figure BDA0002798191560000071
wherein x isnIs from the nth array element distributed along the central line of the array antenna to the linear central position of the array antenna, InIs the normalized excitation amplitude of the nth array element, k is 2 pi/λ, λ is the spatial wavelength, and u is sin θ θ is the azimuth;
step 2: calculating the sidelobe level PSLL (PeakSideLobeLevel) of the peak value, wherein the formula is as follows:
Figure BDA0002798191560000072
in the formula: u. ofsFor side lobe ranges other than main lobe peak, AF (u)s) For any side lobe level, x ═ x1,x2,···,xn]Is the position of an array element;
and step 3: with dmin≥0.5,d max1 or less and
Figure BDA0002798191560000073
taking the minimum sidelobe level PSLL of the formula (2) as an optimization target as a constraint condition, adopting a differential optimization algorithm, and taking a final target function formula as follows:
Figure BDA0002798191560000074
in the formula: dminNormalizing the minimum spacing, d, for the array elementsmaxNormalizing the maximum spacing for the array elements;
solving the objective function to find a group of optimal solutions x ═ x satisfying the optimization objective1,x2,···,xn]，I＝[I1,22,···,In]Obtaining the spacing distribution of the antenna array elements and the excitation amplitude of each array element;
and arranging antenna units at the positions of the obtained antenna array element spacing distribution.
Specifically, the antenna unit is three layer construction, by supreme bottom base plate, intermediate level, top layer base plate of including in proper order down, the bottom surface of bottom base plate sets up the microstrip feeder, and bottom base plate top surface sets up ground plate and coupling groove, the intermediate level is the air bed, the patch antenna array element is placed to the bottom surface of top layer base plate.
Specifically, the coupling slot length determination process in block 103 is as follows:
step 1: the coupling groove is an H-shaped coupling groove, the poynting vector S of the groove part of the H-shaped coupling groove points to two sides from the center, and the vector direction of the S is approximately vertical to the plane of the H-shaped coupling groove;
step 2: the energy W is related to the poynting vector S,
Figure BDA0002798191560000081
in the formula: a is H open slot closed space;
the energy of the H-type coupling slot is calculated by equation (4).
And step 3: under the condition that the size of an array element of the patch antenna is fixed, the length of the middle slotted part of the minimum H-shaped coupling groove and the length increasing value of the middle slotted part of the H-shaped coupling groove are set, the proportional relation between the lengths of different H-shaped coupling grooves and the excitation amplitude is obtained through energy calculation of a formula (4), the length of the middle slotted part of a group of H-shaped coupling grooves is selected to be matched with the required optimal excitation amplitude, and the length of the H-shaped coupling groove is designed.
Specifically, the feed network in the module 104 is formed by cascading T-type power splitters, microstrip feed lines are disposed at output ends of feed lines of branches of the T-type power splitters, the microstrip feed lines extend to a bottom surface of a bottom substrate of the antenna unit, lengths of the microstrip feed lines of the branches are unequal and adjustable, and a mathematical relationship between lengths of the microstrip feed lines is determined based on positions of the array elements.
The utility model provides a low side lobe array antenna structure, includes a N antenna element and feed network, a N antenna element centrosymmetric inhomogeneous distribution, antenna element is three layer construction, including bottom substrate, intermediate level, top layer substrate, bottom substrate's bottom surface is the microstrip feeder, and bottom substrate top surface sets up ground plate and coupling groove, the intermediate level is the air bed, patch antenna array element is placed to top layer substrate's bottom surface, patch antenna array element sets up to square, the coupling groove center sets up at square center, and the microstrip feeder feeds in from paster edge center, and the perpendicular to the coupling groove, feed network divides the ware to cascade for a plurality of T types merit, the microstrip feeder sets up the output at a plurality of T types merit and divides the ware.
Example (b):
the engineering design requirement parameters are as shown in table 1:
TABLE 1 engineering design requirement parameters
Figure BDA0002798191560000091
1) The antenna unit spacing and the excitation amplitude are calculated, the antenna with the low-sidelobe array antenna structure adopts the centrosymmetric and non-uniform distribution of the antenna units, as shown in figure 2, for 2N array elements, delta xnThe distance between the nth antenna element and the nth-1 antenna element is shown, the number of the antenna elements is set to be 8, in order to reduce the mutual coupling effect of the antennas, the minimum distance between the antenna elements is set to be 0.7 lambda, the maximum distance is set to be lambda, the normalized minimum excitation amplitude value is set to be 0.4, and the distance between the antenna elements and the excitation amplitude can be calculated according to the formulas (1), (2) and (3), as shown in table 2.
Table 28 array element antenna array element spacing and excitation amplitude
Figure BDA0002798191560000092
2) The antenna element is designed in a three-layer design, as shown in fig. 3. The bottom layer adopts the thickness of h10.254mm, dielectric constant εr2.2, tan delta 0.0009, the bottom surface of the substrate is an adjustable microstrip feeder, and the top surface is a grounding plate with an H-shaped groove; the middle layer has a thickness of h2An air layer of (a); the top layer has a thickness h30787, the bottom side of which is provided with a patch unit, so that the top substrate can also serve as an antenna cover to protect the antenna. The H-shaped slot can obtain larger coupling under the same size relative to the rectangular slot, and brings convenience to impedance matching, so that the antenna unit is designed to adopt an H-shaped slot, wherein the parameter ll is the length value of the microstrip feeder line passing through the center of the H-shaped slot.
In order to reduce excessive variable parameters and reduce the optimization difficulty, firstly, the antenna unit adopts a square patch to replace a rectangular patch, namely Wp is equal to Lp, and the initial size of the square patch is still obtained by a calculation formula of the rectangular patch. And secondly, placing the H-shaped groove at the center of the patch, and adjusting the microstrip feeder line to feed in from the center of the edge of the patch and be vertical to the H-shaped groove.
The antenna voltage standing wave ratio and directional diagram simulation results are shown in fig. 4 and fig. 5, and it can be seen from fig. 4 that the antenna standing wave ratio is less than 2 and the relative bandwidth is 14.4% in the range of 12.81GHz to 14.85GHz, thereby greatly widening the antenna bandwidth, and as can be seen from fig. 5, the unit gain is only 10dBi, and the level of the side lobe is too high to be applied to engineering, therefore, the antenna is constructed in an antenna unit array mode, wherein the distance between the antenna units is set according to a table.
3) Feed network design
A T-type power divider cascade network is adopted, wherein, as shown in fig. 6, a port a of the T-type power divider is an input port, a port B, C is an output port, and when the output ports have consistent power, that is, the distribution ratio is 1:1, the requirement is met
Figure BDA0002798191560000101
Because the change of the excitation amplitude is realized by the change of the slot length, only a feed network with equal radiation and same phase needs to be designed, the excitation amplitude of the feed network is determined by the power proportion of each T-shaped power divider, the equal excitation amplitude of the array elements can be ensured by keeping the width of the feeder line at the output end of each T-shaped power divider consistent, the phase of the antenna unit is determined by the length of the feeder line from the feed end to the antenna unit, the total length of the feeder line of each branch is equal to ensure that the phases are consistent, each small section of the feeder line of each branch is set as a variable based on the position of the antenna unit, the mathematical relationship of each section is determined, and the feed network is of a symmetrical structure, and only the feeder line relationship at one side of the antenna is constructed, as. By combining the characteristics of coupling feed, a section of same microstrip line is added at each output port, and the impedance matching of the antenna can be quickly realized by adjusting the size of the microstrip line without influencing power distribution. And according to the positions of the antenna units, constructing a one-to-eight parallel feed network, and adjusting the lengths of the corresponding feed lines for multiple times according to the simulation result to enable the simulation result to meet the requirement. The simulation is shown in FIG. 8, the simulation result is shown in FIG. 9, and the power value S of each output port*1Are all around-9 dB and extremelyThe difference is not more than 0.4dB, and the power distribution is basically consistent; meanwhile, the phase curves are basically superposed, and the feed network realizes in-phase excitation in a wider frequency range.
The feed network may be affected in the antenna element energy distribution due to the ground plane slotting and the multi-layer substrate stacks being coupled to each other. The magnitude of the energy obtained by each array element is further explored by the poynting vector S. The relationship between the energy W and the poynting vector S is:
Figure BDA0002798191560000111
in the formula: a is a closed curved surface.
The poynting vectors of the patches and H-coupling slots are shown in fig. 10.
The corresponding relation between the slot length and the energy is obtained through simulation, the energy ratio passing through the slot surface is not completely equal to the slot length ratio, and the energy and the slot length are nonlinear, so that the excitation amplitude ratio cannot be simply replaced by the slot length ratio, the slot length is a key factor influencing gain and impedance matching under the condition that the patch size is determined, the slot length is continuously adjusted through simulation until the excitation amplitude ratio relation is met, and when the input power is 1W, the length and the power of each patch corresponding to the H-shaped coupling slot are shown in a table 3.
TABLE 3 Slot Length and Power Allocation
Figure BDA0002798191560000112
Under the length setting of the H-shaped coupling slot, the energy passing through the H-shaped coupling slot is close to the theoretical value of the excitation amplitude, and the energy received by the patch is approximately considered to meet the design requirement, and the antenna parameters are as shown in table 4.
TABLE 4H-shaped slot broadband antenna parameters
Figure BDA0002798191560000121
The material is shown in figure 11
The test shows that the voltage standing wave ratio of the antenna is shown in fig. 12, and it can be seen that, during simulation, the voltage standing wave ratio of the antenna is less than 1.5 within the range of 13.67-15.48 GHz, during actual measurement, the voltage standing wave ratio of the antenna is less than 1.5 within the range of 13.84-15.5GHz, the bandwidth covers 14-14.5 GHz, and the bandwidth requirement of the transmitting antenna is met.
The directional pattern characteristics of the antenna are observed from three frequency points of 14, 14.25 and 14.5GHz, the simulation and actual measurement results are shown in fig. 13, and the performance ratio of gain, side lobe level and main lobe width is shown in table 5.
TABLE 5 comparison of different frequency point performances of H-shaped slot broadband antenna
Figure BDA0002798191560000122
The gain of the antenna is slightly reduced along with the increase of the frequency, the width of the main lobe is consistent with the variation trend of the gain, and the width of the main lobe is narrower as the gain is higher. The side lobe electricity of three frequency points is lower than-19.5 dB on average, and the antenna array realizes low side lobe in the working bandwidth.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the invention.

Claims (9)

1. A design method of a low sidelobe array antenna is characterized in that a parallel array antenna with non-uniform antenna element spacing is constructed, the design method adopts a differential optimization algorithm to obtain the antenna element spacing distribution with the lowest sidelobe level and the optimal solution of the excitation amplitude of each antenna element, an antenna element is arranged at the optimal solution position of the antenna element spacing distribution, the slotting length of a coupling slot of the antenna element is determined according to the optimal solution of the excitation amplitude, and the microstrip feeder line length of a feeding network of the antenna element is determined according to the optimal solution of the antenna element spacing distribution.
2. The method for designing the low sidelobe array antenna according to claim 1, wherein the optimal solution solving process of the antenna array element spacing distribution and the excitation amplitude is as follows:
step 1: an array antenna pattern function is determined from an Array Factor (AF) function,
Figure FDA0002798191550000011
wherein x isnIs from the nth array element distributed along the central line of the array antenna to the linear central position of the array antenna, InIs the normalized excitation amplitude of the nth array element, k is 2 pi/λ, λ is the spatial wavelength, and u is sin θ θ is the azimuth;
step 2: calculating the sidelobe level PSLL (Peak Side Lobe level) of the peak value, wherein the formula is as follows:
Figure FDA0002798191550000012
in the formula: u. ofsFor side lobe ranges other than main lobe peak, AF (u)s) For any side lobe level, x ═ x1,x2,…,xn]Is the position of an array element;
and step 3: with dmin≥0.5,dmax1 or less and
Figure FDA0002798191550000013
taking the minimum sidelobe level PSLL of the formula (2) as an optimization target as a constraint condition, adopting a differential optimization algorithm, and taking a final target function formula as follows:
Figure FDA0002798191550000021
in the formula: dminNormalizing the minimum spacing, d, for the array elementsmaxNormalizing the maximum spacing for the array elements;
for the above-mentioned objectSolving the function to find a group of optimal solutions x ═ x satisfying the optimization objective1,x2,…,xn]，I＝[I1,22,…,In]Obtaining the spacing distribution of the antenna array elements and the excitation amplitude of each array element;
and arranging antenna units at the positions of the obtained antenna array element spacing distribution.
3. The design method of the array antenna with the low sidelobe according to claim 2, wherein the antenna unit is of a three-layer structure and sequentially comprises a bottom substrate, a middle layer and a top substrate from bottom to top, a microstrip feeder is arranged on the bottom surface of the bottom substrate, a ground plate and a coupling slot are arranged on the top surface of the bottom substrate, the middle layer is an air layer, and a patch antenna array element is arranged on the bottom surface of the top substrate.
4. The design method of a low sidelobe array antenna according to claim 3, wherein the coupling slot determining process is as follows:
step 1: the coupling groove is an H-shaped coupling groove, the poynting vector S of the groove part of the H-shaped coupling groove points to two sides from the center, and the vector direction of the S is approximately vertical to the plane of the H-shaped coupling groove;
step 2: the energy W is related to the poynting vector S,
Figure FDA0002798191550000022
in the formula: a is H open slot closed space;
the energy of the H-type coupling slot is calculated by equation (4).
And step 3: under the condition that the size of an array element of the patch antenna is fixed, the length of the middle slotted part of the minimum H-shaped coupling groove and the length increasing value of the middle slotted part of the H-shaped coupling groove are set, the proportional relation between the lengths of different H-shaped coupling grooves and the excitation amplitude is obtained through energy calculation of a formula (4), the length of the middle slotted part of a group of H-shaped coupling grooves is selected to be matched with the required optimal excitation amplitude, and the length of the H-shaped coupling groove is designed.
5. The design method of a low sidelobe array antenna according to claim 3, characterized in that the feed network is formed by cascading T-type power dividers, the output end of each branch feeder of the T-type power divider is provided with a microstrip feeder, the microstrip feeder extends to the bottom surface of the bottom substrate of the antenna unit, the lengths of the microstrip feeders of each branch are unequal and adjustable, wherein the mathematical relationship of the lengths of the microstrip feeders is determined based on the positions of the array elements.
6. The utility model provides a low sidelobe array antenna structure, its characterized in that, includes a N antenna element and feed network, a N antenna element centrosymmetric inhomogeneous distribution, antenna element is three layer construction, including bottom base plate, intermediate level, top layer base plate, the bottom surface of bottom base plate is the microstrip feeder, and bottom base plate top surface sets up ground plate and coupling groove, the intermediate level is the air bed, patch antenna array element is placed to the bottom surface of top layer base plate, patch antenna array element sets up to square, the coupling groove center sets up at square center, and the microstrip feeder is from paster edge center feed-in, and the perpendicular to the coupling groove, feed network divides the ware to cascade for a plurality of T types merit, the microstrip feeder sets up the output at a plurality of T types merit and divides the ware.
7. The array antenna structure of claim 6, wherein the bottom substrate has a thickness h10.254mm, dielectric constant εrA Rogers RT5800 substrate with 2.2 and tan delta of 0.0009, the top substrate being a thickness h30.787mm Rogers RT5800 substrates.
8. The array antenna structure of claim 7, wherein the antenna element N is set to 8, the distance between two antenna elements with central symmetry is 0.7 λ, the excitation amplitude is 1, the distance between the antenna element distributed to two ends and the previous antenna element is 0.72 λ, 0.75 λ, 0.77 λ, and the corresponding excitation amplitude is 0.89, 0.64, 0.4.
9. A low sidelobe array antenna structure as claimed in claim 8, wherein the coupling slot is H-shaped, the length of the H-shaped slot being 4.5mm, 4mm, 3.8mm and 3.2 mm.
CN202011339428.0A 2020-11-25 2020-11-25 Low sidelobe array antenna structure and design method Pending CN112487632A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114498019A (en) * 2022-04-15 2022-05-13 南京林业大学 Antenna patch, patch antenna, antenna array and electronic equipment

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114498019A (en) * 2022-04-15 2022-05-13 南京林业大学 Antenna patch, patch antenna, antenna array and electronic equipment

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